1. Field of the Invention
The present invention relates to a trigger switch mounted to an electric tool, in detail, a trigger switch comprising a contact mechanism of a spring-reversal type switch suitable for large AC and DC.
2. Prior Art
A conventional trigger switch with a brake contact, which is used for an electric tool, has a structure that an alternate current AC connected to a motor M in series and a switch are provided, as shown in FIG. 18. The switch is arranged so that a movable contact M would be brought into contact with a fixed contact T1 to make a main contact turn on by drawing an operation part provided in the electric tool, and then, the motor M would be supplied with electric power to be rotated although this is not shown in the drawing. Stopping the draw of the operation part causes the main contact to be released from a state of ON. The movable contact M is brought into contact with a fixed contact T2 instead of the above to turn on the brake contact. This causes the motor M to be short-circuited to put on a brake.
As described above, used are the two polar fixed contacts T1 and T2 and the movable contact M wherein one pole is used as a so-called main contact, which is used for supplying the motor M with electric power, and the other pole is used as a so-called brake contact, which causes the motor M to be short-circuited to put on a brake when the motor M is not supplied with electric power (refer to JP-A-2003-162930 (pages 5 to 8 and FIG. 5)).
The switch described in Related Art, however, has a problem that the main contact having a so-called single contact structure is inferior in insulation and life since one of the two polar contacts is used as the main contact while the other is used as the brake contact although the switch has a structure suitable for large AC and DC.